8G SEAWEEDS 



SPOROCHNACE.E. 



General Characters. The sporangia are lateral 

 branches of hairs arising from the superficial 

 cells, and are unilocular. The growth of the 

 thallus is trichothallic, the growing-point being 

 situated in a group of cells at the base of the 

 terminal tuft of hairs. The cells are produced in rows 

 free from each other, but these become united below 

 into a parenchymatous tissue. A thallus of con- 

 siderable size, diversity and beauty of form is 

 characteristic of the group. 



The Thallus, originating as described, is mostly 

 branched on all sides and round or flat in section. 

 The growing branches are crowned each with a 

 tuft of hairs, which falls off on the cessation of growth 

 in length. The parenchymatous cells composing the 

 thallus decrease in size towards the margin, and 

 the more superficial ones contain the bulk of 

 the chromatophores. 



The Reproductive Organs occur in sori or on definite 

 fertile portions of the thallus, and the sporangia are 

 lateral branches of the sporangiophores. The spor- 

 angia are mostly obovate or elongate- ovate in form, 

 and spring in some cases from the base of the spor- 

 angiophores, more frequently at intervals through- 

 out their length. In Nereia the sporangiophores 

 occur in sori, and in the other genera Sporochnus, 

 Carpomitra, Bcllotia, Encyothalia, and Perithalia 

 definite fertile branches of the thallus are produced, 

 of more or less characteristic forms, those of Spo- 



